Amplifying telegraphic signals



Sept. 7 1926.

J. w. MILNOR AMPLIFYING TELEGRAPHIC SIGNALS 2 Sheets-Sheet 1 0 3 6 H w w, L 1

gwuenfoz attorney Sept. 7, 1926. 1,599,382 J. w. MILNOR AMPLIFYING TELEGHAPHI C S IGNALS o i Filed June 11, 1924 2 Sheets-Sheet 2 5 I gnomvlio'u I Patented Sept. 7, 1925 UNITED i STATES 1 1,599,382 PATENTOFFICE.

JOSEPH W. MILNCR, OF NEW YORK, N. '55., ASSIGNORTO THE WESTERN UNION TELE- GRAPH COMPANY, OF NEW YORK, N. Y., A GQRIORA'IION OF NEW YORK.

AMPLIFYING TELEGRAPHIG SIGNALS.

.Application filed .Tnnell, 1924, Serial No. 719,411. Renewed. July '29, 1926.

My invention relates broadly to amplification systems for electrical currents and more particularly to a circuit arrangement for amplifying received telegraphic signals.

One of the objects of my invention is to provide an amplification system for electri-,

cal current particularly applicable to a system in which telegraphic signals from landv ing the feeble high frequency current com ponents of telegraphic signals and causing them to actuate a responsive device while low frequency or direct current components of the signals are by-passed around the mag cause of the low frequency of operation, and

particularly because it becomes desirable, if not absolutely necessary for the magnifier, to be able to pass not only alternating currents of low frequency, but direct currents as well. l-Vhen applied for magnifying tele- I phonic frequencies, an electron tube is usually operated in conjunction with intervalvo transformers. A transformer for use with low frequency telegraph currents has a number which may be mentioned inefficiency and expensive construction. The transformer coupled multistage amplifier is limited to operation with alternating currents and will not pass direct currents. 1

in order to increase the amplitude of feeble direct. current-s, transformer coupling may be supplanted by a resistance method of coupling. However, resistance coupling is undesirable in many respects for it inefficient and has a smaller voltage amplification per stage than is produced in inductively coupled circuits. I

Difiiculties are encoun-,

f inherent disadvantages among In the present invention, the electron tube is used for the magnification of the higher frequency components only, of the received telegraphic signals. The lower frequency components of the telegraphic signals and the direct current components are usually present in such strength that it is unnecessary to magnify them to any extent. The latter current is passed directly from the line into theapparatus or responsive device for reception or recording of signals,

through a suitable impedance for controlling the signals.

My invention will be more clearly. under stood from the following specification by reference to the. accompanying drawings in which; I I Figure 1, is a diagrammatic illustration showing my improved amplification system for electron tubes where the by-pass circuit for the low frequency and direct current components of the telegraphic signals isparallel connected with the amplificationcircuit which transfers the high frequency al= ternating. currentcomp'onents of the telegraphic signals; I I

Figure 2, is a diagrammatic illustration of the combination amplification system nected in theinput circuit of the high frequency amplifier; and v Figure 3, is a detailed wiring diagram: showing the arrangement of anelectron tube amplifier and by-pass circuit for the low frequency and direct current components of the. signals. I

Figure 4 is a diagrammatic illustration illustratingv an alternate arrangement for the low frequency or direct current by-pass circuit ofFigures 1, 2 and 3, embodying a magnifier of the selenium type.

Figure 5 illustrates another modification of my amplifier in which a plurality of electron tubes are employed. I

Figure 6 is diagram showing an arrangement of my amplifier in which the capacity, resistance and inductance are also used to shape the high frequency components of the currents.

Figure 7 is a diagram illustrating an embodiment of my invention in which "I use a common battery for the cathode and space current circuits for a plurality of amplifiers. I I

Telegraphic signals of any description wherein the bypass circuit is series conspo'nsive device.

may be considered to be composed of alternating currents of a range of frequencies. The frequencies of importance range from direct current (or a current of zero frequency)' to a current at. a frequency which is approximately twice as high as the fundamental or dot frequency of the telegraph signals. Ordinarily the low frequency components are passed through the telegraph line and system without great loss. The components of higher frequency become much weakened: in transmission through the line and it frequently becomes quite impor tant to provide apparatus which will in- 1 crease' the strength ofthe components of the line signals at the higher frequencies.

My present invention accomplishes this desired result by the provision of a network for the transfer of the low frequency or direct current components of the received telegraphic signals from the line to' the re- This network may be parallel or series connected with the input circuit of the electron tube amplifier, the

' energy dividing at this point and the rela tivelywea'lr high frequency alternating current components of the signal passing through the electron tube amplifier to the responsive device. 7

Referring. more particularly to the drawings, reference character 8 represents the line system from which weal-I telegraphic signals are received. Numeral 4 represents a"-i eceiving', relaying or recording device,

'' hereinafter referred toas a responsive device, in which the magnified signals are received, and may be used either for operating'l ocal translating devices, such as sound era-printers, etc., or maybe used for working or' repeating into another line section. The electrical signal magnifier or amplifier is rep-resented at l and may be of any type although as representedin Figure 8, an electron tube amplifier is particularly applicable in increasing the feeble received current to such an amplitude that the responsive devicefunctions with accuracy. Numeral 5 represents an impedance network containing resistance, inductance and capacity in any desired combination for modifying the shape of the signals. In lieu of anetworl: 5' a magnifiermay be interposed in the circuit. That is to say, 5 might be a magnifier of the selenium type which is a relatively slow acting magnifier; while 1 might be a magnifier of the vacuum tube type. Of the current received from line 8, a portion is passed directly to receiver 4 through network: 5. The remainder of the received current is passed through amplifier or magnifier f.

The input terminals of the network 5 have been represented by reference numeral (5, while the output terminals are shown at 7.

The. current components of the higher frequen'cy are magnified by amplifier 1, and

the system may include a pluralityof tubes,

but for purposes of illustration, the amplifier has been shownas consisting of electron tube 16 having filament electrode 17, grid electrode 1 8, and plate 20. The line 8 terminating at 2-2', is electrically connected with the input circuit of the amplifier l by coupling coils 21 and 22 of transformer 9. Current of high frequency from line 8 will pass through condenser 15 and. energize primary coil 21 of amplifier 1. Secondary coupling coil 22 is connected with filament electrode 17 and grid electrode 18, comprising the input circuit of the electron tube 16. The output circuit of the tube 16 includes primary winding 23 of coupling transformer 2, inductively coupled with secondary winding 25, having terminals 33-, delivering the high frequency current component to the circuit of the responsive device 4, including win-ding 14. The cathode 17 is heated from battery 26 and space current supplied from battery 27. It will be understood that while only a single stage of elec tron tube amplification has been shown any desired number of tubes may be used with a plurality of intervalve coupling transformers.

The network 5' may contain any desired combination of inductance,- resistance and capacity, and for illustrative purposes it is shown as containing inductance 28 and resistance 29;

It-willbe observed that only direct current and alternating current of low frequency from line 8 will reach coil 13 of responsive device 4, through network 5, while current of higher frequency passes through amplifier l and is magnified and impressed upon Winding 14 of the responsive device 4.

The amplifier circuit may be grounded as shown at 12, reducing the tendency of the system to oscillate. This is a particular feature of my circuit arrangement, the system being rendered non-oscillatory to all practical purposes. Vi here the line systems terminate in a telegraph office and employ a.

i Gil tween the several circuits,

as illustrated in Fig. 7 a

I have shown in Figure 4 a magnifier of the selenium type to be substituted for the network 5. .31 isv a moving coil of the DArsonval galvanometer type, 32 is a mirror attached to or driven by the coil 31, 33 is light source including an optical system, 34 and 35 are selenium cells forming two arms of a l/Vheats tone bridge, 37' and 38 are resistances forming the remaining arms of the bridge, 36 is a battery connected across fleeting the light beam 50,- so that more of the light beam rests on selenium cell 34 and less on cell 35, or vice versa, depending upon the polarity of the signals. This causes the electrical resistance of cell to decrease and of cell 35 to increase, or vice versa, thus unbalancing the bridge. Hence a current, which is an amplified reproduction of the low frequency and direct current components of the telegraph signals, flows in outputleads 7. The characteristics of this magnifier are such that it is insensitive to high frequencies, and hence it will have a relatively unimportant effect on the high,

frequency components of the signals.

In Figure 5, I have shown an alternate organization for the arrangement 1, for amplifying the high frequency components in which a plurality of electron tubes are used, which includes, in addition to the, arrangement shown in Fig. 3, the intervalve coupling transformer 39, with primary winding 40 and secondary winding 41; electron tube 45, having filament electrode 47, grid el-ctrode 46 and plate 48. The action here is similar to that of the amplifier 1 of Figure 3, described elsewhere, except that, due to the use of a plurality of tubes, a higher degree of amplification is secured.

In Figure 6, I have shown the amplifier for the high frequency components of the signal currents in which the capacity 43, resistance 44 and inductance 49 also serve to shape the high frequency components. have also shown the use of an auto-trans former 42 instead of the usual transformer, in the output of the electron amplifier.

In the operation of my circuit arrange ment, the energy received over the-line is divided, the relatively weak portions of the received signals being amplified, and other portions of the received energy not magnis fied but passed directly to the responsive device, the action of the responsive device being controlled partly by the current from the magnifier, and partly by the current taken directly ,fromtlie line.

l/Vhile I have described my invention in certain particular embodiments, it will be understood that modifications may be made and that no limitations upon the invention are intended other than are imposed by the scope of the appended claims.

l/Vhat I claim and desire to secure by Letters Patent of the United States is as follows:

1. An amplification system for electrical signals having a' plurality of differing current components, comprising in combination,-

a source of signal energy comprising com-- ponents having different characteristics, an input circuit. conductive tocertain of said components, an amplifier connected with .said input circuit, an output circuit connected with said amplifier, connections between said output circuit and a responsive device, and an electrically conductive circuit conductive to other of said components between said source of signal energy and .said responsive device, whereby said amplifier operates to transfer current components of one character1st1c to said responsive device while said electrically conductive circuit operates to transfer current components of differing characteristics also to said responsive device.

. 2. An amplification system for electrical si nals havino'a luralit of differin com-v b e g ponents, comprising in combination,a source of signal energy comprising components having different characteristics, an input circuit conductive to certain of said compo nents, an amplifier connected with said input circuit.v an output circuit connected with said amplifier, connections between said output circuit and a responsive device, and means electrically conductive to certain of said current components to which said amplifier is non-conductive for also impressing a plurality of current components upon said responsive device.

- 3. A signal receiving system comprising in combination, a source of signal energy comprising components having different characteristics, a responsive device actuated by substantially all of said components, and a plurality of parallel electrical paths each responsive to differing current components of said signal energy, connected between said source of signal energy and said responsive device, whereby a plurality of current components of said signal energy are caused to simultaneously actuate said responsive de- Vice. I

4. A signal receiving system comprising by substantially all of said components, a plurality of parallel electrical paths each responsive to differing current components of said signal energy connected betweensaic source of signal energy and said responsive device, and means in one of said paths for increasing the amplitude of the current components therein, whereby all of said current components are caused to actuate said responsive device.

5. A system for receiving telegraphic nected between said line circuit and said responsive device for also impressing low frequency and direct current components of said signals upon said responsive device.

6. A system for receiving telegraphic signals having a plurality of differing current components comprising in combination a line circuit, a responsive device actuated by substantially all of the components of the received signals, and a pair of circuits connected between said line circuit and said responsive device, one of said circuits operating to impress hi 'hfrequency current components of the received signal upon said responsive device, and the other of said circuits operating to impress low frequency and direct current components of said signal upon said responsive device.

7. A system for receiving telegraphic signals having a plurality of differing current components comprising in combination a line circuit, a responsive device actuated by substantially all of the current components of the received signals, a. pair of circuits connected between said line circuit and said responsive device, one 01" said circuits operating to impress high frequency current components of the received signal upon said responsive device, and the other said circuits operating to impress low frequency and direct current components oi said signal upon said responsive device, and means interposed in one of said circuits for increasing the amplitude of the current coin onent therein.

A system for receiving telegraphic signals having ap-lu-rality of d iiiering currant component-scomprising in combination a line ci cuit, a responsive device actuated U sub ntially all of the current components of the received signals, a pair of circuits connected between said line circuit and said responsive device, one of said circuits operating'to impress high frequency current components of the received signal upon said r snonsiverdevice, and the other of said cirnseegssa cuits operating to impress low frequency.

and direct current components of said signal upon said responsive device, and means interposed in said first mentioned circuit for increasing the amplitude: otsaid high frequency current components upon the responsive device;

9. A system for the reception. of telegraphic signals having components of differin characteristics com risin in com--' circuit and said responsive device for impressing low frequency and also direct current components of said signals upon. said responsive device.

10. A system for the reception of teler: iic signals having components of dif i 1 g characteristics, comprising in comb'nation a line wire circuit, an electron tube amplifier having input and output circuits,

responsive device, connections between said line wire circuit and the input circuit of said amplifier for impressinghigh frequency current components of said signals thereon, connections from the output circuit of said amplifier to said. responsive device, and an impedance circuit connected between said line wire and said responsive device "for transferring low frequency and direct current components of said signals upon said responsive device.

11. A system for the reception of telegraphic signals having components ofdifi'ering characteristics comprising in combination a line wire circuit, an electron tube amplifier having input and output circuits, responsive device, connections between said line wire circuit and the input circuit of said amplifier for impressing high frequency 1 C(HRPQI ts oi said signals thereon, connections from the output circuit ofsaid amplifier to said responsive device, and a circuit containing a plurality of electrically conductive elements connected between said line wire and said responsive device for transferring low frequency and direct current components of said signals upon said responsive device.

12. A system for the reception of telegra irhic signals having components of differing characteristics, comprising in 'combination a line wire circuit, an electron tube amplifier having input and output circuits, a responsive device, connections between said wire circuit and the input circuit of said amplifier it'or impressing high frequency current components oi saidsi-gnals thereon,

Ill)

a connection from the output circuit of said amplifier to said responsive device, and a network connected between said line wire circuit and said responsive device for transferring low frequency and direct current components of said signals upon said responsive device, whereby said responsive device is operated simultaneously by all of said current components.

13. The method of receiving telegraphic signals which'consists in receiving a plurality of current components of the telegraphic signals over a line, dividing the current components thus received into two sets, amplifying one set of current components and causing them to actuate a responsive device and impressing the other set of current components directly upon said responsive device.

14. The method of receiving telegraphic signals which consists in receiving a plurality of signal current components of varying degrees of strength over a line, dividing the weak current components of said telegraphic signals from the stronger current components thereof, amplifying the weak current components and .impressing them upon a responsive device and directly impressing said stronger current components upon said responsive device. I Y

15. The method of receiving electrical signals having a plurality of di'ifering' our rent components, which consists in dividing vture.

the current components received, amplifying and modifying the wave shape of one set of said components and causing them to actuate a responsive device and also impressing another set of said current components upon said responsive device.

16. A signal receiving system as set forth in claim l, one of said paths containing means for shaping the wave shape of the current components passing therethrough.

17. A signal receiving system comprising in combination, a source of signal energy, comprising components having different characteristics, a responsive device actuated by substantially all of said components, a plurality of parallel electrical paths each responsive to differing current components of said signal energy connected between said source of signal energy and said responsive device, and means'in more than one of said paths for increasing the amplitude of the current components therein, whereby all of said current components are caused to actuate said responsive device.

18. A' signal receiving system as set forth in claim e, one or more of said paths containing means for shaping the wave shape of the current components passing through. I V

In testimony whereofI affix my signa- JOSEPH w. MILnon.

there- 

